What three scientists long ago helped the cell theory?

The three scientists who contributed significantly to the development of the cell theory are Matthias Schleiden, Theodor Schwann, and Rudolf Virchow. Schleiden, a botanist, proposed that all plants are composed of cells. Schwann, a zoologist, extended this idea to animals, stating that all living organisms are made up of cells. Virchow later added to the theory by proposing that cells can only arise from pre-existing cells, challenging the idea of spontaneous generation.